Combustion behavior and soot formation/oxidation of oxygenated fuels in a cylindrical constant volume chamber

Oxygenated fuels produced from methane-based products, are currently being studied in several research centres for their capability of strongly reducing soot at the exhaust of internal combustion engines.In the present activity different oxygenated fuels were investigated in a constant volume chamber with large optical access. In order to study the combustion evolution and soot formation and oxidation processes, optical techniques such as OH chemiluminescence and two dimensional two color pyrometry (2D2CP) have been applied. Moreover a fast particle spectrometer has been used at the chamber exhaust in order to analyze the soot emissions from the different investigated fuels. Poly(oxymethylene) dimethyl ethers (OME) with a CH3–O–(CH2–O)n–CH3 general molecular structure have been studied for different temperatures at start of combustion.The first phase of the investigation included the calculation of the kL factor for three OME2 in diesel blends. The results demonstrate a reduction of the soot formation dominated phase when increasing the oxygenated fraction in the blend. Moreover fuel jet images show a reduction of the soot formation area when increasing the oxygen content in the blend. The second phase of the activity focused on exhaust emissions by means of a Cambustion DMS 500 fast particle spectrometer. Results highlighted nearly smokeless combustion for pure oxygenated fuels and a non-linear soot emission reduction with increasing O2 content in the blend.